Well after the confirmation of new DSi exclusive games arriving this fall, the first of these has been announced- Monster Finder. It's being developed by Alpha Unit, a third party developer.

"Titled Monster Finder, this original game has players use the DSi Camera to capture monsters, then face them off in battle. The game promises over 100 monster designs, created by character designer Matsuda."

... At first, I thought this was some kind of "Monster Hunter For Kids" game, because of the name. O.O How the camera could be used to capture monsters though... Who knows? Could work, might not work. D:

While I don't hold out much hope for the quality of 3rd-party DSi-exclusives either, if they accomplish nothing else perhaps flashcart teams will be able to analyze them and start figuring out how to update their products to work in DSi mode so homebrew developers will be able to start making apps for the DSi that use its features.

Camera based to capture monsters so...
A) Image recognition so when you snap a picture of a cat, get a tiger 'monster' in game
B) A 'snap a pic of a barcode' from a package, can of beans, etc. and you get some monster.
C) It could be some sort booster pack of cards tie-in with some sort of code that the game recognizes. You snap a pic to get the monster in game.

I think both the random bar code and trading card tie-in based games have already been tried in one form or another over the years.